This invention is directed to methods for improving the rates of transalkylation reactions among benzenoid species. This invention is also directed to means for the improvement of mixtures of benzenoid species to improve their utilities for petrochemical and fuel use.
The preparations of alkyl benzenes is known generally to provide products comprising isomeric and stoichiometric mixtures. It is also known to prepare para xylene, 1,4 dimethylbenzene, through a disproportionation reaction of toluene, methylbenzene. This reaction is known to provide a proportion of trimethylbenzene derivatives whose removal is desired from the final product.
Those skilled in the art will appreciate that numerous other examples are known wherein the preparation of certain alkylbenzenes produces a proportion of undesirable polyalkylbenzene byproducts. Such persons will similarly appreciate that the removal of such byproducts from a mixture of benezoid spaces renders the mixture substantially improved from the point of view of efficiency, commercial utility, and product yield. Accordingly, means for such removal are highly desired.
It is known that transalkylation among benzenoid species will take place under acid catalysis at high temperatures. It is also known, however, that acid catalysis will promote intramolecular isomerization of alkyl benzenoids.
The foregoing acid catalyzed transalkylation and isomerization reactions of benzenoids has been used for the removal of undesired polyalkylated benzenes from mixtures of benzenoid species. The rates of the foregoing reactions at low temperature are slow, however; the costs to accomplish such removal of undesired species is concomitantly high.